The book you cannot finish may still contain a sentence you keep.

Books are usually judged as whole objects, either read or abandoned, as though value only arrives at the last page. Plenty of them give you one line that stays for years while the rest slides off entirely. The exchange was still worthwhile, and the guilt about the bookmark stuck at page sixty is a tax you have chosen to pay for no reason.

Give yourself permission to stop at the point where a book stops giving you anything. Copy out the sentence you want to keep before you put it aside. Then read something you actually want to be inside.